In the art, the axial and central semi-rigid strength member 7 may be referred to as a “central strength member”, and the cable as stripped as shown in FIG. 1 may be said to be “prepared”.
In view of the mechanical weakness of optical fibers, it is necessary for a watertight inlet via which an optical cable can enter a chamber or a container to be provided not only with sealing means, but also with strong means for securing the outer sheath 2 of the cable and its strength members, such as the peripheral strength members 5, 6, or the central strength member 7 and its associated flexible peripheral strength members.
Currently, the Applicant sells an elongate metal securing solepiece that is in the form of a rigid metal bar whose downstream end is provided with a clamping piece for securing the optional central strength member, and whose upstream end is provided with a pair of notches for receiving a clamping collar for clamping the outer sheath of the optical cable against said bar, the upstream notches being followed downstream by two pairs of notches for receiving two securing collars for securing the peripheral strength members.
Once the optical cable has been prepared, then put in place and clamped onto the securing solepiece, the resulting assembly is threaded into the container, and the securing solepiece is fixed by means of screws to a place provided for that purpose in the container. Then, the cable inlet is sealed either by using a heat-shrinkable sleeve, or by pouring in a sealing resin, or else (in other known and analogous devices) by using a conventional stuffing-box sealing device.
Such known cable inlet devices suffer from the drawbacks of being quite voluminous in the longitudinal direction, and of being awkward to use because it is necessary to act positively in the container to fix the securing solepiece therein by means of screws, while access to the inside of the container is often difficult. In addition, the cable inlet sealing is positioned before the place where the outer sheath is secured, so that any external stresses on the cable are applied initially to the sealing device (heat-shrinkable sleeve, sealing resin, stuffing box, etc.), and only then to the sheath securing device. As a result, such a cable inlet device is not very reliable because the sealing device is not always designed to be capable of withstanding external stresses for very long.